proposal: golang plugin hub

[doujiang24]

motivation:
benefits from the golang ecosystem, people could easily implement plugins, for more long tail scenes.
we could build a plugin hub, so that people could contribute plugins to the hub, and reuse plugins.
similar to the traefik: https://plugins.traefik.io/plugins

technical details:

1. each plugin is a golang module, with a valid go.mod.
2. each plugin could declare its own config proto, default to TypedStruct.
3. people could push config through control-plane, i.e. EnvoyFilter for istio.
4. furthermore, the hub could provide a way to combine plugins into a big plugin, to reduce cgo calls which might be a bit heavy cost.

[wbpcode]

Will this a new independent repo?

[phlax]

this seems like a good idea to me - i think we should host it under the envoyproxy project

@doujiang24 i think we can get started with this in a separate repo and existing example plugins and then transfer it, add some docs, etc, once it has grown a bit

cc @mattklein123

[doujiang24]

yep, a separate repo should be good enough for starting, and we could transfer it when it is ready to ship.

[mattklein123]

I like the idea of a hub but I think it should stay a totally separate project. SGTM to host with this org.

[phlax]

somewhat relatedly - im wondering about the "canonical" way to compile a plugin - with the example we use envoy build container which is quite a heavy toolchain to add - iiuc we can compile with just the stream api and deps - maybe i dont uc tho

i mention because i guess that would be a kinda first step for a repo - some CI that tests plugins using the "canonical" build method, and also in terms of docs/contribs we probably want to publish the easiest way possible to get started

[doujiang24]

yep, it only depends on the Go compiler and the C compiler (since cgo is enabled) to compile a Go plugin, so we don't need the envoy build image to build a Go plugin. i.e. we could use the golang docker image.

[zengyuxing007]

Looking forward to it, so envoyproxy's ecology can be more rich up！

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in the next 7 days unless it is tagged "help wanted" or "no stalebot" or other activity occurs. Thank you for your contributions.

[doujiang24]

This is under early design. Please add no-stale label, thanks! cc @phlax